Depends on the compost and how fine it is. You might find that only a trace of sand is needed.
Organic material breaks down and sand doesn't, so you end up with proportionately more sand than you put in. Must continually add more organic material.
My boxies' outdoor habitats are pure compost. The substrate has great drainage, and also holds moisture well.
My RT habitat was built one summer when I had no finished compost. I had to buy top soil. It isn't the same at all. There were times when I tossed sand in to dry it up after the habitat got too wet & wouldn't dry. Times it's too dry.
I add compost to the habitat, and eventually that will comprise most of it.
If your soil is heavy clay, then sand is a good additive. I don't think sand is terrible in small quantities, sometimes its good, but some people are unalterably agin it.
I have a large enclosure and I did half peat miss and half organic topsoil. Whenever I decide I need to add more I usually add more dirt than Pete Moss.